Not just for train travel, but also for bus, train or taxi travel, HopStop gives you directions, plus schedules for over 140 destinations in Europe, New Zealand, Australia, Canada and the United States.

If you're traveling in the UK this app will give you up-to-date information on train schedules and lets you know when there has been a disruption. You can purchase your tickets here as well, though your purchase will be made through a third party.

https://play.google.com/store/apps/details?id=uk.co.nationalrail.google or https://itunes.apple.com/gb/app/national-rail-enquiries/id519094154?ls=1&mt=8